Industrial gas flow systems are typically complex systems requiring a multiplicity of mechanical connections between many and varied fixtures and plumbing. The complexity of these gas flow systems is reflected in the industry jargon describing these systems, "gas jungles". Prior art gas jungles have a number of inherent limitations and disadvantages.
The multiplicity of mechanical connections required in such systems reduces the overall reliability of such systems. The complexity of the configuration increases particulate generation and provides more particulate entrapment zones. The multiplicity of mechanical connections, moreover, increases the costs associated with such systems in labor required to fit connections, auto weld joints and provide tubing bends.
In addition, integrity maintenance such as leak detection and/or control for such systems is a cumbersome and time consuming procedure. The integrity of the multiplicity of mechanical connections is a more critical factor where the gas jungle experiences acute extremes in temperature as in those gas flow systems subjected to heating and/or cooling to vaporize and/or condense fluids flowing therethrough. The multiplicity of fixtures and the complexity of the interconnecting plumbing configuration, moreover, limits access to the components of the system for maintenance and/or repair.
The mechanical complexity of gas jungles for industrial applications such as vacuum chemical vapor deposition (V-CVD) systems presents matters of additional concern. V-CVD systems utilize volatile and/or toxic gases to grow thin films such as polysilicon, silicon nitrides, high and low temperature silicon dioxide, tetraethoxy silane and phosphosilicate glass on silicon wafer substrates. Loss of mechanical integrity in such systems may have adverse or disastrous consequences.
There are additional configuration or functional constraints associated with prior art gas jungles. The plumbing configurations of some prior art gas jungles do not positively isolate flow streams of diverse gases. Certain elements of the gas jungle such as check valves and filters are independent elements requiring additional time and mechanical connections for integration into the jungle.
Prior art switching valves are preconfigured for a particular application and must be removed from the system and reconfigured for different applications. In addition, some gas flow systems require that the switching valve be positioned at the same elevation as the mass flow controller.